IV The Impact of Population Growth on Economic Welfare-Nontraditional Elements Harvey Leibenstein In an age when there is unusual concern about the population explosion one would think that the concern arises as a result of a solid understanding of the consequences of population growth on the economy. However, much of what is normally understood about the consequences of population growth depends upon the classical approach to the problem. The primary mode of analysis involves inferences about output based on the impact of population growth on the ratios of the traditional inputs of land, labor, and capital. Only in recent years have we had hints that we may be on the wrong track. The viewpoint taken in this paper is that a more useful approach is to consider the problem in terms of a number of nontraditional elements that are likely to be important in determining the rate of economic growth. To be specific, our analysis will emphasize the impact of population growth on those acquired qualities of the population that are important to output and its growth. THE CLASSICAL MOLD OF THE POPULATION-RESOURCES PROBLEM The essence of the classical mode of thinking is to emphasize physical resources in relation to population; therefore, land and capital are the basic resources considered. Behind this mode of thinking is the notion of a unique production function. That is to say, there is a one-to-one relation between the inputs for land, labor, and capital and the output that results—for every set of inputs there is a unique and determinate output. Since it is usually argued that land and other natural resources are fixed, then at some point the rela- Harvey Leibenstein is Member of the Center for Population Studies and Andelot Professor of Economics and Population, Department of Economics, Harvard University.ion Growth,"